1. Field of the Invention
Example embodiments generally relate to a fixing-device, and more particularly, to a fixing device using induction heating and an image forming apparatus using the fixing device.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, printers, facsimile machines, or multifunction printers having at least one of copying, printing, scanning, and facsimile functions, typically form a toner image on a recording medium (e.g., a sheet) based on image data using electrophotography. Thus, for example, a charger charges a surface of an image carrier; an optical writer emits a light beam onto the charged surface of the image carrier to form an electrostatic latent image on the image carrier according to the image data; a development device develops the electrostatic latent image with a developer (e.g., toner) to form a toner image on the image carrier; the toner image is then transferred from the image carrier onto a sheet; and finally, a fixing device applies heat and pressure to the sheet bearing the toner image to fix the toner image on the sheet, thus forming the toner image on the sheet.
In order to save energy, one example of the fixing device includes an induction heater to heat a heating roller or a fixing belt that applies heat to a sheet bearing a toner image to fix the toner image on the sheet. The induction heater provides a higher heat exchange rate than a halogen heater, for example, and thereby decreases a time period needed for the fixing device to heat up to a proper fixing temperature after the fixing device is powered on.
In a high-speed image forming apparatus for forming an image at a high speed, the fixing device is upsized to provide a longer fixing nip at which heat and pressure are applied to a sheet bearing a toner image. The upsized fixing device has a larger heat capacity and thereby uses more heat. Therefore, in order to heat the upsized fixing device up to the proper fixing temperature quickly, power is cut off to devices other than the fixing device included in the image forming apparatus in order to be able to supply more power to the fixing device.
More specifically, the induction heater uses an inverter to generate a high-frequency current, which in turn requires that the inverter needs to be larger to generate more power, and accordingly, the induction heater coil needs to be larger as well. At the same time, however, the maximum electric power consumption available to the image forming apparatus varies depending on the country where it is used. When the image forming apparatus is manufactured to correspond to the largest maximum electric power consumption available for all destination countries, the induction heater is upsized, thus increasing the size of the image forming apparatus overall at a time when market demands favor more compact image forming apparatuses